Self-fill and flow control safety valve



Nov. 5, 1968 L. cv KNOX ET AL 3,409,078

- SELF-FILL AND FLOW CONTROL SAFETY VALVE Original Filed June 29, 1966 2Sheets-Sheet l Hm H02 INVENTORS LLOYD CARTER KNOX JOHN w. woons sogqagiflam, fimh w m ATTORNEYS I Nov. 5, 1968 KNOX ET AL 3,409,078

SELF-FILL AND FLOW CONTROL SAFETY VALVE Original Filed June 29, 1966 2Sheets-Sheet 2 INVENI'ORS LLOYD CARTER KNOX JOHN W. WOODS ATTORNEYSUnited States Patent 3,409,078 V SELF-FILL AND FLOW CONTROL SAFETY VALVELloyd Carter Knox and John W. Woods, Duncan, Okla}, assignors toHalliburton Company, Duncan, 'Okla., a

corporation of Delaware 7 Original application June 29, 1966, Ser. No.561,588, new Patent No. 3,385,370, dated May 28, 1968. Divided and thisapplication Nov. 13, 1967, Ser. No. 698,084

2Claims. (Cl. 166-21) ABSTRACTHOF THE DISCLOSURE A method forcontrolling the flow of fluid into a casing string as the string isbeing lowered in a well, and includ ing a valve for controlling 'fluidflow during cementing operations. Thevalve apparatus is positionedadjacent the lower end of a pipe string and includes a tubular bodyhaving a downwardly facing valve seat. A valve elementis mounted in thebody and biased upwardly for movement into engagement with the valveseat. The tubular body has a plurality of radial ports that are closedby the valve element when it is in engagement with the valve seat. Thevalve element has a central port that is closed by a second valveelement. Above the first valve element there is an upper valve seat anda third valve that is movable upwardlyv into engagement with the uppervalveseat. The second and third valve elements are biased upwardly anddownwwardly, respectively, but are connected together by a frangiblelink. While the casing string is being lowered in the bore hole thevalve remains closed until a predetermined pressure differential buildsup on the outside of the valve. The valve then opens and fluid flowsinto the casing. If the rate of fluid flow into the casing exceeds apredetermined rate', the third valve element closes against the uppervalve seat. The valve assembly is converted to a" float valve by pumpingfluid down the casingstring at a high rate to break the frangiblelink.

V This is a division of application Ser. No. 561,588, filed June 29,1966, now Patent No. 3,385,370. I

.This invention relates to well. apparatus for controlling the flow offluid through a pipe, and more particularly to apparatus for controllingthe flow .of fluid into a casing string as it is being run into a borehole and for controlling the flow of fluid during cementing and similaroperations.

After a bore hole has been drilled, the hole may be cased to prevent itfrom' caving in. In accordance with common practice, a string of pipe isrun in the bore hole ice s such a rapid rate that 'the fluid wouldblowout at the top of the casing string. This can be prevented by shuttingoff the flow of fluid into the bottom of the pipe and applying pressureto overcome the formation pressure. I

During the cementing operation, cement is pumped down the casing stringand out at the bottom of the pipe.

When the cement has been placed in the annular space between the outsideof the casing pipe and the wall of the well bore in this manner, thehydrostatic pressure of the cement tends to cause the cement to flowback into the casing string. Therefore, it is necessary to provide aback pressure valve to resist the hydrostatic pressure at the bottom ofthe casing string. The back pressure valve must open in response tofluid pressure in the pipebeing greater than the fluid pressure on theoutside of thepipe to allow the cement to pass out of the bottom of thepipe. Thus, the back pressure valve operates as a check valve.

The self-fill valve for filling the casing string while it is being runin the bore hole opens under just the opposite fluid pressureconditions. Thus, several valves which are seemingly incompatible arerequired in carrying out casing placement and cementing, and relatedoperations. One conventional method of controlling the flow in'a wellcasing is to use plugs or balls which are dropped in the casing stringto trip a valve or to render it inoperative. Of course, if plugs orballs are used, it is necessary to have a clear passage through theentire casing string to permit the plugs or balls to pass down to theposition of the valve, near the bottom of the casing string. Ifintermediate tools are inserted in the casing string, such as multiplestage cementing collars or packers, then the use of plugs or balls tooperate valve below the level of these tools may be awkward orimpossible.

Accordingly, it is an object of this invention to provide a self-fillcollar or shoe that incorporates a flow control safety valve.

It is a further object of this invention to provide flow controlapparatus which is operated by fluid pressure rather than by plugs orballs dropped down the casing string.

It is a still further object of this invention to provide apparatus forautomatically controlling filling of the casand cement is pumped downthe pipe. The cement flows In lowering the casing .string, it isdesirable to gradually.

fill the pipe with fluid to reduce the pressure differential between theinterior and exterior of the pipe. There should be a slight differentialin pressure, however, to keep the fluid in the pipe from overflowing atthe top of the casing string, since the mud and water would spill on thecrew and on the rig'floor. A pressuredifferential of about 90 to 100pounds per square inch pressure between the interior and the exterior ofthe casing string would normallyprevent fluid in the casing string fromoverflowing.

As the casing string is being lowered in the well bore, there is alwaysthe possibility of the well starting to come in. If this happens,theformation pressure may force the ing to maintain a predeterminedpressure diflierential while preventing excessive flow rate of fluidinto the easing string These objects are accomplished in accordance witha preferred embodiment of the invention by providing in a casing stringa valve assembly including a flow rate valve element which isselectively converted to a back pressure valve, An upwardly openingdifferential pressure valve element is seated on a downwardly openingcementing valve. The differential pressure valve opens upwardly when thefluid pressure in the annular space outsidethe casing. string is greaterthan the pressure in the interior of the casing string. The flow ratevalve element and the differential pressure valve are each mounted on avalve stem and the valve stems are rigidly joined together by afrangible link. The flow rate valve element is normally held away fromits valve seat by the spring biasing the differential pressure valveagainst its seat.

. Thus, opening of the differential pressure valve moves the flow ratevalve element toward the valve seat, but normally the flow rate valveremains spaced from the seat to permit flow upwardly when thedifferential pressure valve opens. By increasing the pump pressure onthe fluid in s the casing string, the frangible link may be broken. Whenfluid into the pipe at the bottom of the casing string at pressure in,thebore hole. The diflerential pressurevalve,

element moves with the cementing valve since it is spring biased againstthe cementing valve. Displacement of the cementing valve uncovers radialports in the tubularbody of the collar or shoe. Fluid which is flowingdown the casing string isdirected outwardly through the ports into theannular space outside the casing pipe and above the lower end ofthepipe. A pin mounted in the tubular body restrictsdownwarddisplacement of the differential pressure valve element, while thecementing valve continues to move downwardly in response to fluidpressure in the casing string. Thus, cement that is pumped down thecasing string flows radially outward through the .ports in the sideofthe tubular body and also downwar ly through the orifice in thecementing valve that is no longer covered by the differentialpressurevalve element. The combination of the radial ports and a bottomoutlet provides .a thin. a al pwa is mountedjor axial sliding move; mentin the tubular body 8. A shoulder 46 in the body 8 forms a valve seatagainst which the orifice valve 44 is urged by a spring 48. The orificevalve 44 has a central opening 50 through which the valve element 38extends. A circular riibber gasket 52 in the interior of the valve 44fits closely around the valve element 38 to prevent the leakageToffluid.llpwardly pasttheflvalve element 38 when the valve is in theposition shown in FIG. 1. I r v H Directly below the valve'element-38isa pin.54 which projects upwardly from a mounting ringr56. Thering 56has a plurality of'axial passages 58 to permit the flow of fluid throughthe rings. A guide" 60 is secured on the lower end of the tubular-body 8and a central opening in turbulence to give a better cement bond. Therate of filling the casing can be adjusted by changing the size of theorifice in the center of thecementing valve or the spring bias on thediflerential pressure valve element.

This preferred embodiment is illustrated in the accompanying drawings inwhich: Y

FIG. 1 is a cross sectional view of the apparatus of this invention asmounted in a shoe on the lower end of a casing string;

FIG. 2 is a cross sectional view of the shoe during filling of thecasing string;

FIG. 3 is a cross sectional view of the apparatus after the frangiblelink has been broken to convert the safety valve to a back pressurevalve; and

FIG. 4 is a cross sectional view of the apparatus showing the positionsof the valve elements while cement is being pumped down the casingstring.

Referring to FIG. 1, the valve apparatus of this invention isillustrated in the drawings in the form of a shoe 2 mounted on the lowerend of a casing string 4. The

casing string is suspended in a bore hole 6.

The cementing shoe 2 has a tubular body 8 which is provided with threadsat its upper end for being secured to the casing string 4. A tubularcollar 10 is mounted in the body 8 adjacent the upper end. The collar 10has a central passage 12 and a conical portion 14 of the passage forms avalve seat. A valve guide 16 is secured in the tubular body below thecollar 10 and is held in place by a snap ring 18. The valve 16 has aplurality of axial ports 20 to permit fluid to flow through the valveguide. A central bore 22 in the valve guide supports a valve stem 24 foraxial sliding movement relative to the valve guide. The valve stem 24has a valve element 26 formed on its upper end. An abrasion resistant,resilient cover 28 is molded on the valve element 26. The cover 28 isprefthe guide 60 communicates with the well bore below the shoe 2.Radial'ports62 in-the tubular body 8 also communicatewiththe well bore,but are spaced above the guide60, ,4 The valve element 38 is urgeddownwardly by a spring 64 with suflicient force to maintain the flange40 against the top wall of theorifice valve44, but the force of thespring 64is not sufficient to displace the orifice valve 44 away fromthe valve seat 46 in opposition to the spring 48. h v

Fluid pressureon the outside of thetubular body 8, is imposed on thevalve element 38, since the valve element 38 is in communication withthe well bore through the guide 60. When the fluid pressure below thevalve element 38 is greater than the pressure above the element 38, thepressure differential urges the valve element upwardly relative to the,orifice valve 44, as shown in FIG. 2. Preferably, a pressuredifferential of between 90.and 100 pounds per square inch between theinterior of the casing string and the bore hole is sufficient todisplace the valve element38 upwardly to the position shown in FIG. 2.Since the valve stems 34 and 24 are rigidly connected together, theupper valve element 26 is also displaced toward the valve seat 14, butthe valve element 26 does not engage the seat 14 under normal conditionswhile filling the casing string.

If the rate of fluid flow into the casing string shouldincrease due toan abnormally high pressure differential, the fluid pressure acting onthe valve element 38 imposes an axial force urging the element 26 intoengagement with the valve seat 14. The radial flange 30 on the element26 also contributes to shutting off of the flow'of fluid into the casingstring. The valve element 26 will remain in engagemerit with the seat 14until the pressure differential is reerably formed of rubber andconforms in shape and size to the valve seat 14. A flange 30 extendingaround the periphery of the cover 28 is pressed tightly against thevalve seat 14 by fluid pressure when the valve element 26 engages thevalve seat 14. The valve element 26 is urged upwardly toward the valveseat 14 by a spring 32, which is compressed between the valve elementand the guide 16.

A second valve stem 34 is secured to the lower end of the valve stem 24by a pin 36, which rigidly connects the adjacent ends of the valve stems24 and 34 together. As shown in FIG. 1, the upper end of the stem 34 hasan axial bore to receive an axial projection on the stem 34. The pin 36extends transversely through the stems 24 and 34, so that a downwardforce on the stem 34 imposes a transverse shearing force on the pin 36.The pin 36 is selected to shear off when a predetermined force isimposed downwardly on the valve stem 34. The lower end of the stem 34has a valve element 38 including a radial flange 40. A circular disk 42formed of a flexible resilient material overlies the flange 40 toprevent the leakage of fluid downwardly past the valve element 38.

A11 orifice valve 44, having a cylindrical side wall and duced either byincreasing the pressure in the well casing string, or by reducing thefluid pressure in the bore hole.

Circulation may be established at any time during the running of thecasing string into the bore hole. By pumping fluid down the pipe, thefluid pressure in the tubular body 8 above the valve element 38 isincreased sufliciently to displace the orifice valve 44 downwardly awayfrom the valve seat 46. Downward movement of the valve stem 34 isrestricted by the spring 32, since the spring is compressed between theupper valve element 26 and the valve guide 16. Thus, the circulationfluid flows outwardly through the ports 62, and flows downwardly throughthe orifice 50 provided that the orifice valve .44 is displaceddownwardly away from thevalve element 38.

The flow control valve element 26 is converted to a back pressure valveby pumping fluid down the pipe at a rapid rate so that the force on thedisk 42 and the flange 40 imposed by the fluid pressure above the valveelement 38 is sufliciently great to break the shear pin 36 connectingthe valve stems 24 and 34. As shown in FIG. 3, when the pin breaks, thevalve element 26 is urged upwardly against the valve seat :14 by thespring 32 to allow fluid to flow past the valve 26 only in a'downwarddirection.

During the cementing operation, cement is pumped down the casing stringunder sufiicient pressure to displace the valve element 26 away from thevalve seat 14 and to displace the valve element 38 and the orifice valve44 downwardly. Since the valve -element 38 is no longer restricted inits downward movement by,the upper spring 32, the flange 40 remainsagainst the top wall of the orific'e valve 44 as the valve 44 movesdownwardly. When the valve element 38 engages the pin 54, furtherdownward movement of the valve element 38 is'pr'evented, although theorifice valve 44 continues to move downward until it reachesapproximately: the position shown in FIG. 4. When the valve element 38and the orifice valve 44 are in these relative positions, cement flowingdownwardly through the tubular body 8 passes around the edge of theflange 40 and outwardly through the radial ports 62. A portion of thecement also passes downwardly through the orifice 50 in the valve 44 andout through the guide 60 at the bottom of the tubular body 8.Discharging the cement through ports in the side of the body 8 and atthe same time through the bottom guide 60, causes an improved cementbond due to the turbulence produced.

In operation, the cementing shoe 2 is secured on the lower end of thecasing string 4. As the casing string is being lowered in the bore hole,the casing remains dry inside until a predetermined pressuredifferential builds up on opposite sides of the orifice valve 44. Whenthis pressure differential is reached, the valve element 38 is displacedupwardly to permit flow through the orifice 50. When the pressuredifferential across the valve element 44 drops below the predeterminedvalue, the spring 64 displaces the valve element 38 downwardly to theclosed position, as shown in FIG. 1. If the flow of fluid into thecasing string through the orifice 50 exceeds a predetermined rate, thedynamic fluid pressure on the flange 40 compresses the spring 64 untilthe upper valve element 26 engages the valve seat 14. For a two andseven eighths inch outside diameter pipe, the rate of flow required formoving the valve element 26 into engagement with the seat 14 is abouttwo barrels per minute. The rate of flow required for closing the valvemay be adjusted by changing the springs 32 or 64, or by using adifferent size orifice 50.

To circulate, fluid is pumped down the casing string under suflicientpressure to displace the orifice valve 44 downwardly to the positionshown in FIG. 4, thereby allowing the fluid to be discharged outwardlythrough the ports 62. When the fluid pressure in the casing string isreduced, the spring 48 returns the orifice valve 44 to the positionshown in FIG. 1. Normally, the circulation rate is not suflicientlygreat to break the shear pin 36. A circulation rate of 4 barrels perminute, for example, may be used to shear the pin 36. The valveapparatus is then converted to a float shoe and cementing can be carriedout utilizing the valve element 26 as a back pressure valve to preventthe cement in the annual space between the casing and the bore hole fromflowing back into the casing string.

When the cement is pumped down the casing string after the pin 36 issheared, the valve element 26 is displaced downwardly by the fluidpressure differential and the valve element 38 and the orifice valve 44are displaced to the positions in FIG. 4. The cement flows through theorifice 50 and downwardly through the guide 60. A portion of cement alsoflows outwardly through the ports 62, which add turbulence along theside of the tubular body 8 to provide a better cement bond.

The valve apparatus of this invention maintains a differential pressurebetween the inside and the outside of the pipe while the casing stringis being lowered into the bore hole. This prevents the casing stringfrom. overflowing at the top. The valve apparatus also provides a flowrate control to shut off the flow of fluid in the'event that the wellstarts to come in. The valve apparatus permitscirculation to be carriedout at any time while the casing string is being run in the bore hole.Furthermore, the valve apparatus may be readily converted to a down-jetfloat shoe. During the cementing operation, the cement is conducedthrough the side of the shoe and also downwardly through the bottom ofthe shoe, and the-turbulence produced results in an improved cementbond.

The valve apparatus and method of this invention has been describedherein as used in carrying out cementing operations, but the inventionis not limited to the particular operations described. The apparatus andmethod may also be used in fracturing or other operations, where it isnecessary to pump fluid down the pipe string and to control the rate offluid flowing into the pipe string.

While this invention has been illustrated and described in oneembodiment, it is recognized that variations and changes may be madetherein without departing from the invention set forth in the claims.

We claim: 1. A method of controlling fluid flow through a casing stringin a bore hole comprising the steps of:

lowering a casing string having a valve assembly into a bore hole,

opening said valve assembly while lowering said casing string inresponse to greater fluid pressure in the bore hole outside the casingthan inside the casing string,

preventing a continued upward flow of fluid in said casing string abovesaid valve assembly in response to an upward flow rate of fluid intosaid casing string greater than a predetermined rate,

pumping fluid down said casing string to alter said valve assembly inresponse to said downward flow and thereby preventing subsequent upwardflow of fluid through said casing string,

opening said valve assembly in response to a greater fluid pressure insaid casing than in said bore hole, and subsequently closing said valveassembly in response to a greater fluid pressure in said bore hole thanin said casing.

2. The method in accordance with claim 1 including pumping fluid downsaid casing string to establish circulation while lowering the casingstring, said circulation step being carried out prior to said pumpingstep.

References Cited UNITED STATES PATENTS 2,630,178 3/1953 Brown 166--2252,642,140 6/ 1953 Brown 166225 2,698,054 12/1954 Brown et al. 166-225 X3,062,296 11/1962 Brown l66225 3,126,060 3/1964 Loiacano 137-5l5 X3,223,159 12/1965 Brown 166-21 DAVID H. BROWN, Primary Examiner.

